1. Cells and Their Environment
Biology with Mr. D.

2. I. Cell membrane Semi-permeable function
Lets only certain molecules through.

3. A. Passive Transport
Substances move across membrane without using energy
1. Diffusion is an example
Molecules move from an area of high concentration to a lower concentration.
(down a concentration gradient)

4. 2. Osmosis
Type of passive transport where water moves across a semi-permeable membrane

5. 3. Facilitated diffusion
When molecules move across the cell membrane with the help of proteins.

6. B. Active Transport
Uses energy to transport molecules across the cell membrane. (ATP)
Ex. Sodium-potassium pump

7. II. Solution Concentrations
A. Hypertonic
Solution with a higher concentration of solutes
B. Hypotonic
- Solution with a lower concentration of solutes
C. Isotonic
-Concentration is the same on both sides

8. III. Bulk Movement

9. A. Exocytosis
Wastes are secreted out of the cell

10. B. Endocytosis Cell membrane surrounds a molecule and engulfs it.
1. Phagocytosis- takes in solid material
2. Pinocytosis- takes in liquid material